Reactivity of the phosphinidene-bridged complexes [Mo _2Cp(μ-κ ~1:κ ~1,η ~5-PC _5H _4)(η ~6-1,3,5-C _6H _3 ~tBu _3)(CO) _2] and [Mo _2Cp _2(μ-PH)(η ~6-1,3,5-C _6H _3 ~tBu _3)(CO) _2]

摘要

The cyclopentadienylidene-phosphinidene complex [Mo _2Cp(μ- κ ~1:κ ~1,η ~5-PC _5H _4)(η ~6-*)(CO) _2] (1) (Cp = η ~5-C _5H _5; Mes* = 2,4,6-C _6H _2 ~tBu _3) reacted with RC≡CR′ in refluxing toluene solutions to give the corresponding phosphide derivatives [Mo _2Cp{μ-κ ~1, η ~5:κ ~1,η ~1-(C _5H _4)PCR=CR′}(η ~6-*)(CO) _2] (R = R′ = CO _2Me; R = H, R′ = CO _2Me, p-tol), displaying a phosphametallacyclobutene ring. In contrast, the phosphinidene complex [Mo _2Cp _2(μ-PH)(η ~6-*)(CO) _2] (2) reacted with MeO _2CC≡CCO _2Me at room temperature to give first the monocarbonyl phosphide-acyl complex [Mo _2Cp _2{μ-κ ~1:κ ~1, η ~3-PHC(CO _2Me)=C(CO _2Me)C(O)} (η ~6-*)(CO)], the latter evolving progressively to the isomeric dicarbonyl [Mo _2Cp _2(μ-κ ~1: κ ~1,η ~1-PHC(CO _2Me)=C(CO _2Me)}(η ~6-*)(CO) _2] (Mo-P ca. 2.57 ?). When different ligands such as CO, PMe _3, P(OMe) _3, or CNXyl were added at room temperature to toluene solutions containing compound 1 and different alkynes, relatively fast multicomponent reactions took place to give with good yields the corresponding phosphide-acyl complexes [Mo _2Cp{μ-κ ~1,η ~5: κ ~1,η ~1-(C _5H _4)PCR= CR′C(O)}(η ~6-*)(CO) _2] (R = R′ = CO _2Me; R = H, R′ = CO _2Me, p-tol), and [Mo _2Cp{μ-κ ~1,η ~5:κ ~1, η ~1-(C _5H _4)PC(CO _2Me)=C(CO _2Me)C(O)}(η ~6-*)(CO)(L)] (L = PMe _3, P(OMe) _3) or the related phosphide-iminoacyl derivatives [Mo _2Cp{μ-κ ~1,η ~5:κ ~1, η ~1-(C _5H _4)PCR=CR′C(NXyl)} (η ~6-*)(CO) _2] (Xyl = 2,6-C _6H _3Me _2; R = R′ = CO _2Me; R = H, R′ = CO _2Me, C(O)Me), respectively, all of them displaying five-membered phosphametallacyclopentenone or phosphametallacyclopentenimine rings. Separate experiments revealed that the latter complexes (R = R′ = CO _2Me) could be decarbonylated photochemically to yield the corresponding monocarbonyls [Mo _2Cp{μ-κ ~1,η ~5: κ ~1,η ~3-(C _5H _4)PC(CO _2Me)=C(CO _2Me)C(X)}(η ~6-*)(CO)] (X = O, NXyl), the latter rearranging at room temperature to give the corresponding phosphametallacyclobutene isomers [Mo _2Cp{μ-κ ~1, η 5:κ ~1,η ~1-(C _5H _4)PC(CO _2Me)=C(CO _2Me)}(η ~6- *)(CO)(CX)]. A side product was also formed during the photochemical treatment of the dicarbonyl substrate, it being finally isolated after chromatographic workup as the alkenylphosphide-chloride complex [Mo _2CpCl{μ-κ ~1,η ~5:κ ~1, η ~2-(C _5H _4)PC(CO _2Me)=CH(CO _2Me)}(η ~6-*)(CO)] (Mo-P = 2.553(2) and 2.436(2) ?).